After multiple rounds of fundraising, some of China’s most valuable private technology companies are turning to a less common way of raising capital: Issuing convertible securities.

Ride-hailing giant Didi Chuxing Technology Co. is in talks with potential investors about a sale of bonds that could later be exchanged into stock shares in the Beijing-based company, according to people familiar with the matter. It isn’t known how much Didi is trying to raise in this manner, but the company recently accelerated talks about a potential...